Over the years various types of illuminating assemblies and devices have been developed for indoor and/or outdoor illumination, such as torches, oil lamps, gas lamps, lanterns, incandescent bulbs, neon signs, fluorescent bulbs, halogen lights, and light emitting diodes. These conventional prior art illuminating assemblies and devices have met with varying degrees of success.
Incandescent light bulbs create light by conducting electricity through a thin filament, such as a tungsten filament, to heat the filament to a very high temperature so that it glows and produces visible light. Incandescent light bulbs emit a yellow or white color. Incandescent light bulbs, however, are very inefficient, as a high percentage of energy input is lost as heat.
Fluorescent lamps conduct electricity through mercury vapor, which produces ultraviolet (UV) light. The ultraviolet light is then absorbed by a phosphor coating inside the lamp, causing it to glow, or fluoresce. While the heat generated by fluorescent lamps is much less than its incandescent counterparts, energy is still lost in generating the UV light and converting UV light into visible light. If the lamp breaks, exposure to mercury can occur. Linear fluorescent lamps are often five to six times the cost of incandescent bulbs but have life spans around 10,000 and 20,000 hours. Some fluorescent lights flicker and the quality of the fluorescent light tends to be a harsh white due to the lack of a broad band of frequencies. Most fluorescent lights are not compatible with dimmers.
Conventional fluorescent lights typically utilize a bi-pin/2-pin means on the tubular body that mechanically supports the body in an operative state on lamp holders of the ceiling lighting fixture and effects electrical connection of the illumination source to a power supply. A ballast associated with the lighting fixture converts AC line voltage to the DC power provided to the florescent tube. The ballast also reduces the power supply to a voltage level suitable for use in a florescent tube. A starter circuit for providing a voltage pulse is needed to cause current to conduct through the ionized gas in the fluorescent tube.
Light emitting diode (LED) lighting is particularly useful. Light emitting diodes (LEDs) offer many advantages over incandescent and fluorescent light sources, including: lower energy consumption, longer lifetime, improved robustness, smaller size, faster switching, and excellent durability and reliability. LEDs emit more light per watt than incandescent light bulbs. LEDs can be tiny and easily placed on printed circuit boards. LEDs activate and turn on very quickly and can be readily dimmed. LEDs emit a cool light with very little infrared light. LEDs come in multiple colors which are produced without the need for filters. LEDs of different colors can be mixed to produce white light.
The operational life of some white LED lamps is 100,000 hours, which is much longer than the average life of an incandescent bulb or fluorescent lamp. Another important advantage of LED lighting is reduced power consumption. An LED circuit will approach 80% efficiency, which means 80% of the electrical energy is converted to light energy; the remaining 20% is lost as heat energy. Incandescent bulbs, however, operate at about 20% efficiency with 80% of the electrical energy lost as heat.
Linear LED tube lighting products for replacing fluorescent lighting typically comprise an array of LEDs mounted on one or more circuit boards. The LED boards are mounted on an elongate heat sink comprising a heat conducting material such as aluminum. The LED circuit boards are in thermal contact with the heat sink, but electrically isolated from the heat sink. The LED tube lamp may include internal driver module containing circuitry for converting AC line current to DC current and controlling the voltage applied to the LEDs. The internal driver circuitry can be designed specifically to meet the electrical requirements of the LED circuit boards, thus overcoming potential problems associated with using the existing local ballast originally designed for powering fluorescent lamps. In some designs, however, an external local ballast is used. The high power LEDs, as well as any internal driver module, generate heat that must be dissipated by the heat sink. To facilitate heat dissipation to the atmosphere, the heat sink is typically disposed such that its external surface forms a portion of the outer surface of the tube lighting assembly. The lighting assembly is installed such that the heat sink faces upward toward the ceiling lighting fixture. The remaining circumference of the tube comprises a translucent or transparent lens cover through which the generated light is emitted. The lens cover faces towards the space to be illuminated when the LED lighting assembly is installed in a ceiling or other lighting fixture.
The linear LED lamp heat sink is typically fabricated of an electrically conductive metallic material such as aluminum or aluminum alloys. These materials dissipate heat efficiently without a significant increase in surface temperature. The heat sink itself, as well as the printed circuit LED boards and other electrical components within the linear LED tube assembly, present a safety hazard without proper electrical grounding. This is because the line voltage or voltage input to the LED boards could be applied to the heat sink in the event of a short circuit, for example, if the insulation between the LEDs and/or internal driver circuitry and the heat sink is inadequate or deteriorates during use. This could lead to other components within the assembly overheating and creating a fire hazard. It also creates an electrical shock hazard should the user come into physical contact with the heat sink when inspecting the installed lamp. The electrical components within the lamp, such as LEDs and driver circuits, are also susceptible of being damaged in the event of a power surge. With the recent introduction of sensors, cameras, control and data communications circuitry and other “smart lighting” components into linear LED lamp formats, a comprehensive protective grounding system is required.
One type of LED tube lamp is designed for the insert and rotate type lamp holders mounted on conventional fluorescent ceiling lighting fixtures, known in the industry as “tombstone” lamp holders. Such lamp holders are designed to engage electrical power pins projecting in cantilever fashion from the ends of a cylindrical shaped fluorescent tube lamp, or LED replacement tube lamp. The exposed pins on the ends of the linear LED tube are susceptible to damage during distribution and installation. The lamp body must be situated in a first angular orientation to direct the pins into the lamp holders mounted on a support/reflector and is thereafter turned to effect mechanical securement and electrical connection. Installation requires a precise initial angular orientation of the body and subsequent controlled repositioning thereof to simultaneously seat the pins at the opposite ends of the body. Often one or more of the pins are misaligned during this process so that electrical connection is not established. The same misalignment may cause a compromised mechanical connection whereupon the body may escape from the connectors and drop so that it is damaged or destroyed.
Further, the connectors on the support/reflector are generally mounted in such a fashion that they are prone to flexing. Even a slight flexing of the connectors on the support might be adequate to release the pins at one body end so that the entire body becomes separated. The conventional bi-pin and tombstone lamp holder connector means was created for very lightweight fluorescent lighting and not designed for LED tubular lighting that has additional weight due to the required heat sink and PCB boards. The weight of the body by itself may produce horizontal force components that wedge the connectors on the support/reflector away from each other so that the body becomes precariously situated or fully releases.
U.S. Pat. No. 8,434,891 to Ham proposes a LED tube and socket assembly adapted from the conventional insert and rotate type lamp holder system. The disclosed LED tube features a three pin interface projecting from each end of the tube wherein a middle pin is connected to the heat sink. The lamp holder includes a ground terminal, which receives the middle pin and in turn is connected to an external ground via a ground strap. While this approach provides a grounded heat sink, it does not overcome the above-mentioned problems associated with utilizing external pins in an insert and rotate lamp holder for securing linear LED tube lamps. It does not provide ground protection for the electrical components and circuitry of the lamp.
Moreover, the user is not prevented from inadvertently installing the three-pin lamp ends in a conventional, non-grounded tombstone holder rather than the grounded counterpart replacement holders proposed by Ham. Doing so results in a non-grounded lamp, although visually the installation looks nearly identical to a properly grounded lamp. There is no reliable means of assuring that the holders are replaced and the installation properly performed, and it is difficult to determine by visual inspection whether an installation was performed properly to create a safe grounded system. It is impractical to disassemble the system to check that the conventional fluorescent lamp holders were replaced with grounded lamp holders and that ground straps were connected to the system ground. This presents a significant difficulty for end users, lighting maintenance personnel, building inspectors, safety regulators and others desiring to confirm that replacement LED tube lamps are safely grounded. These difficulties are even more pronounced in commercial environments, such as retail space, warehouses and office buildings, whose overhead lighting systems may utilize hundreds or even thousands of linear tube lamps.
An alternative snap-fit connector system adapted for LED linear tubes is shown in U.S. Patent Application Publication 2014/0293595, by the same applicant of the subject application, and is incorporated as if reproduced in its entirety herein. The tubular LED lighting assembly has at least one LED emitter board within the body; and first and second connectors respectively at the first and second body ends that are configured to secure the lamp on a support fixture. The first connector has cooperating first and second parts. The first connector part is integrated into an end cap assembly of the lamp body. The second connector part is configured to be on a support for the tubular lighting assembly.
The first and second connector parts respectively have first and second surfaces. As the second connector parts connector part is received within an opening of the end cap assembly, the first and second surfaces are placed in confronting relationship to prevent separation of the first and second connector parts as an incident of the first connector part moving relative to the second connector part from a position fully separated from the second connector part in a substantially straight path that is transverse to the length of the lamp body. The snap-fit connection does not utilize exposed pins to mechanically secure the lamp ends to the support and is effected by a linear motion rather than an insert and rotate technique. The first end cap assembly includes at least a first connector board. The connector board comprise generally L-shaped pins housed within the end cap assembly, each having a first portion extending in a direction generally parallel to the length of the body and a second portion extending in a direction traverse to the length of the body and towards the second connector part when said first connector part is moved towards the second the second connector part and into the engaged position. The conductive components on each of the first and second connector parts electrically connect to each other to form an electrical path between the illumination source and an external power supply as an incident of the connector parts being moved into the snap-fit engaged configuration.
The above-mentioned snap-fit connector system addresses some of the problems associated with the use of conventional tombstone type lamp holders for securing LED tube lamps to lighting fixtures. However, it maintains the LED tube lamp in an operating state without providing a means for ground protecting the LED tube heat sink or the internal electrical components of the lamp, thus creating safety and reliability issues for the lamp installation. There is a need for a connector system designed for the unique needs of LED lamp technology that alleviates all safety concerns and provides a safe, reliable and convenient solution that will allow the benefits of LED lamp technology to be fully realized and can be implemented in a cost-effective manner.